Incandescent electric lamp



- UNITE-1') STATES PATENT OFFICE.

EDXVABD P. THOMPSON, OF ELIZABETH, NEIV JERSEY.

INCANDESCENT ELECTRIC LAMP.

.SPECIPICATION forming part of Letters Patent No. 371,003, dated October 4, 1887. Application filed February 28, 1887. Serial K0522909 4. (No modeld To all whom it may concern.-

Be it known thatI, ED\VARD P. THOMPSON,

acitizen of the United States, residingin Elizabeth, in the county of Union and State ofNew Jersey, have invented certain new and useful Improvements in Incandescent Electric Lamps, ofwhich the following is aspecification.

The invention relates to the construction of incandescent electric lamps and to the method of connecting them in circuit, the object being to provide a lamp capable of being turned down or ofgiving but a small amount of light Evhenever itis desired to reduce the illuminaion.

The invention consists, in general terms, in constructing a small section of the filament of an incandescent electric lamp in such manner that it may be included in a separate circuit, or included in different secondary electric circuits derived from electric converters independently of the remaining portion of the filament at will. This small section may then be employed,to the exclusion ofthe remaining portion of the filament,whenever but asmall illumination is desired.

In the accompanying drawings, Figure 1 illustrates an incandescent electric lamp, together with a system of circuits, embodying the features of the invention, and Fig. 2 illustrates the application of the invention to a chandelier. Fig. 3 illustrates a modification.

Referring to the figures, A represents an incandescent-electriciamp globe, and Bits filament. The leading-in wires a and a support the filament in the usual manner. A third wire, a leads to a point, a, a short distance above the point at which the leading-in wire a terminates. Thus there is included between the wires (6 and a ashort section, b, of the filament. It is designed that this section shall be included in the circuit when but a dim light is required.

The invention is illustrated as applied to a system of electric distribution in which electric converters or secondary generators are employed for delivering the currents to the lights. In this instance E represents a suit able source of intermittent or alternating electric currents,whioh are conveyed by conductors L L to the'primary coil P of a converter,O. The secondary coil S has its respective termi- 'leads to the leading-in wire a.

nals connected with conductors Land L, from which the conductors Z Z are derived. These latter conductors lead, respectively. to the terminals of the leading-in wires a a In this manner alternating currents are delivered to the lamp as required.

WVhen it is desired to reduce the light, a switch, 8, included in the conductor Z, may be opened, thus interruping the connections to the leading-in wire (L The conductor Pleads from this leading-in wire to one terminal of the secondary coil 8 of a converter, 0. Acon ductor, Z, leads from the other terminal of this coil to the leading-in wire a The primary coil p of the converter 0 is included in a circuit, Z Z, derived from the conductors Z and 1*. A switch, 8, included in the conductor Z when closed, completes the connections th rough the primary coil of the converter 0. This converter may, if necessary, reduce thepotential of the current, so that the current delivered through the conductors Z I shall be much less than that delivered to the primary coil 1) and adapted to render incandescent the small section b of the filament B. This section may,if desired, be of a different specific conductivity from the remaining portion of the filament. It will thus be seen that by opening the switch 3 and closing the switch 8 the main portion of the filament maybe cut out of circuit and the section I) included in the circuit of the secondary coil of the converter 0. This organization will be found convenient for night-lamps and similar purposes.

Referring to Fig. 2, the inventionis illus trated as applied to a chandelier. In this instance the conductors L L lead through thesupport of the chandelier to the leading-in wires a of, as before. The switch s serves to make and break the connections to the terminal a. The leading-in wire-a. is connected by the conductor 2* with a switch, 8-, which serves to make and break the connections of the circuit when turned by means of the handle t, in any convenient manner,and the conductor l leading from this switch, passes to one ter minal of the secondary coils of the converter 0. The other terminal of this coil is connected through conductor Z to the conductor L which In this manner the section b of the filament may beinr co (No Model.)

W. H, IVERS.

PIANO FORTE.

Patented Oct. 4, 1887.

Wzzzames. 

